A man who was charged with raping and killing his 4-year-old stepdaughter was reportedly beaten to death by inmates at the prison in the border city of Reynosa in the northern part of Tamaulipas, Mexico.

Sergio Oros Sanchez reportedly attacked his stepdaughter on April 26 after his wife left for work. When he realized the brutal attack had left the child unresponsive, he rushed her to a private physician who then referred Sanchez to a hospital, Breitbart reports.

At the hospital Sanchez said his stepdaughter received the injuries during a fall, but medical personnel called authorities as the injuries pointed to physical abuse. He was arrested on April 26 -- the girl was pronounced dead that day. While in custody, Sanchez reportedly told authorities that he had abused the girl in March as well.

Police in the state of Tamaulipas confirmed on May 2 that Sanchez had died from injuries he sustained during a fight at the prison. Officials told Breitbart that he was the target of an inmate "welcoming party," in which prison justice is served to those charged with abusing or murdering children.

Inside the prison, significant power is wielded by inmates who are members of the Gulf Cartel, according to JammedUp News. The Reynosa prison was the site of a bloodbath in 2008 when members of the Gulf Cartel turned on former associates, Los Zetas, who had recently begun to operate independently.

The official death toll of the prison riot was listed as 21, but eyewitness accounts give a much higher figure. Many of the bodies were reportedly incinerated.